Answer:
x = 8
Step-by-step explanation:
The mean is the average of the population.
Multiplying the mean by 8 terms will get you the total sum.
12 * 8 = 96
Subtracting all the values from the total sum should get you x.
96 - 18 - 15 - 18 - 3 - 3 - 19 - 12 = 8